Preparation of α-Imino Aldehydes by [1,3]-Rearrangements of O-Alkenyl Oximes

The synthesis of alpha-imino aldehydes has been achieved through the thermal [1,3]-rearrangement of O-alkenyl benzophenone oximes. A copper. mediated C-O bond coupling between benzophenone oxime and alkenyl boronic acids provides facile access to the required O-alkenyl oximes and a Horner-Wadsworth-Emmons olefination can be applied to the a-imino aldehyde products to give gamma-imino-alpha,beta-unsaturated esters. The scope of the method is described and mechanistic experiments are discussed.